Waterproofing and sealing your foundation from the exterior can be an expensive and disruptive process. When the home or it’s addition is under construction the choice seems fairly easy. A good rubberized membrane application will do the trick. However as in the case of most existing homes, if yours has been completely backfilled and landscaped, an extensive external repair is no easy proposition. What about my plants, my sidewalk or porch, is all that going to have to be removed ?? So you’re telling me on top of the cost of the repair I am also going to have to pay for new cement and landscaping. UGGH !!!
Over the years several different techniques of no digging external repairs have been attempted. Some successful some not quite so good. But do not get discouraged as with most initial applications the products used have been refined to the point that a properly done installation can last for years.
What is this product you ask ?
“Bento-nite grout” is a high solid grout consisting of a proprietary blend of sodium bentonite and other natural minerals that when combined with water will form an organic waterproof slurry. This slurry acts as a remedial sub soil waterproof membrane. With the recent addition of polymer agents this product no longer breaks down due to soil conditions making it an ideal solution for situations where other repair techniques are not viable.
” Bento-nite grout” has been around for decades. It has been used primarily for repairs of man holes, subway tunnels and underground utility vaults. ” Bento-grout ” works with all types of substrates. These include brick and masonry foundations, clay tile and limestone walls and poured concrete as well.
There are application methods available from both the interior and exterior of the foundation.
Due to restraints in equipment an exterior application can only be done to a depth of ten feet. If the area to be seal in excess of 10 feet an interior application can be used in conjunction with the exterior repair to get to the required depth. The first step is to create spud holes in the ground. A spud rod in the shape of the letter ”T” is made from 1/2 inch galvanized piping and has a hardened metal tip at the end. Using a sledge hammer force the rod in the ground all the way down to the footer. Using this technique a series of holes are created approx. 2-3 feet appart and as close to the wall as possible. The spud rod is removed and an injection rod is inserted into the hole. The two rods look the similar except the injection rod has a series of holes drilled near the bottom to allow the “Bento-nite grout” to escape. The other notable difference is an adapter is mounted at the top so the hose from the pump can be connected to the rod.
“Bento-nite grout” is pumped in a fluid state ( about the consistency of a lumpy oat meal) against the exterior of the foundation where it sets up to a more solid mass resembling that of a thick pudding. This forms a high performance impermeable waterproof barrier around the structure. The injection continues until the material is noted coming from either an adjacent hole or between the soil and the foundation. In order to insure the best coverage on the foundation the injection rod is slowly lifted out of the ground during the injection process.
While an exterior applications are the primary technique used for “Bento-nite grout” injection there are instances where an interior application is required. These would be when the desired depth is beyond 10 feet or thru the wall or floor slab of say an elevator pot.
For interior application a series of 1” holes drilled completely thru the wall. Normally this is done in a 3 foot staggered grid pattern. Next a metal packer complete a with ball vale is secured into the hole and connected to the hose from the pump, Injection continues into each packer until either the material flows freely from an adjacent hole or the back pressure is too great to continue. Once all the injection is complete the packers are removed and the holes capped off with a rapid set mortar.
There are a number of benefits to ” Bento-nite grout” injections. First and foremost is the fact that it an exterior basement waterproofing that requires no digging. Secondly “Bento-nite grout” coats the exterior of the wall where it stops the water infiltration before it can penetrate the structure and further corrode the reinforcing steel. Because it remains in a pliable state ” Bento-nite grout” unlike other material that dry ridged is self healing. Lastly ” Bento-nite grout” is a completely organic compound thus it is a completely green application therefore environmental friendly.
“Bento-nite grout” does provide a reasonable alternative to full perimeter full depth excavations .
Written by Walter Slowinski